SEDL / STP / STP386-EB / STP43777S

Resistance of Polymers to Degradation

Atlas, S. M.
Bronx Community College and Polytechnic Institute of Brooklyn, New York,

Mark, H. F.
Bronx Community College and Polytechnic Institute of Brooklyn, New York,

Pages: 8    Published: Jan 1965

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Abstract

Several factors contribute to the rate of degradation of organic polymers under the influence of chemical reagents such as acids, bases, oxygen, or ozone, and of micro-organisms or enzymes:

1. The presence and frequence of chemical bonds which react in principle with these ingredients. These are eventually severed by such action. Bonds of this type are: -C-O-, -C-S-, -C-N-, -C=N-, C=C, and -Si-O-, in contradistinction to -C-C-, which is much more difficult to attack.

2. The atoms or groups in the nearest proximity of these sensitive bonds which either activate or protect them. Such atoms or groups are F, Cl, OH, NH², COOH, CH³, CF³, etc.

3. The supermolecular character of the polymer: oriented, amorphous, crystalline, folded, crosslinked, etc., which does not affect the intrinsic chemical reactivity of the sensitive bonds but influences very profoundly their accessibility and, therefore, the rate of actual degradation.

The discussion of these three factors gives a reasonable explanation of polymer stability, offers useful working hypotheses for improvements, and stimulates the proper selection of stabilizers.